Crystal structure and conformational analysis of 1-[N-(2-bromophenyl)]naphthaldimine

1-[N-(2-bromophenyl)]naphthaldimine (C₁₇H₁₂NOBr) (1) was synthesised and its crystal structure was determined. The compound 1 is orthorhombic, space group P2₁2₁2₁ with a=12.653(2), b=13.7311(14), Z=4, R=0.032 for 499 reflections I>2σ(I)]. There is an intramolecular hydrogen bond of distance 2.473(3) Å between the hydroxyl oxygen atom and imine nitrogen atom, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformation was calculated as a function of torsion angle θ (C10-C11-N1-C12) varied every 5 degrees. The optimized geometry of the crystal structure corresponding to the non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by hydrogen-hydrogen repulsions between the ortho-hydrogen atoms on the aldehyde rings. Complementary IR, ¹H NMR and UV measurements in solution and in the solid state were carried out.     

Single crystal structure and Raman spectrum of Ba3Na2(CN2)4

The synthesis, single crystal structure determination, and Raman spectrum are reported for colorless transparent tribarium disodium tetracyanamide, Ba₃Na₂(CN₂)₄. The title compound crystallizes in the space group C_2h⁵-P2₁/c (#14, , , , β=110.454(4)°, , Z=4, R/wR=0.0266/0.0543). Each sodium atom is surrounded by six nitrogen atoms in octahedral geometry. Sodium centered nitrogen octahedra are linked through face-sharing along the [100] direction to form one-dimensional (1D) chains. These chains are connected to each other through the carbon atoms of cyanamide and make a three-dimensional (3D) network with 1D channels along the [100] direction. Barium atoms and additional cyanamide anions reside in the channels. Each barium atom is irregularly coordinated with nitrogen and carbon from the cyanamide anions. The Raman spectrum shows symmetric vibrations of [NCN]²⁻ corresponding to ν_sym (1241.5 cm⁻¹) and 2δ (1356.4 cm⁻¹).     

The disordered structures and low temperature dielectric relaxation properties of two misplaced-displacive cubic pyrochlores found in the Bi2O3-MO-Nb2O5 (M=Mg, Ni) systems

The disordered structures and low temperature dielectric relaxation properties of Bi_1.667Mg_0.70Nb_1.52O₇ (BMN) and Bi_1.67Ni_0.75Nb_1.50O₇ (BNN) misplaced-displacive cubic pyrochlores found in the Bi₂O₃-M^IIO-Nb₂O₅ (M=Mg, Ni) systems are reported. As for other recently reported Bi-pyrochlores, the metal ion vacancies are found to be confined to the pyrochlore A site. The B₂O₆ octahedral sub-structure is found to be fully occupied and well-ordered. Considerable displacive disorder, however, is found associated with the O′A₂ tetrahedral sub-structure in both cases. The A-site ions were displaced from Wyckoff position 16d (, , ) to 96 h (, , ) while the O′ oxygen was shifted from position 8b (, , ) to Wyckoff position 32e (, , ). The refined displacement magnitudes off the 16d and 8b sites for the A and O′ sites were 0.408 Å/0.423 Å and 0.350 Å/0.369 Å for BMN/BNN, respectively.     

Ab initio and DFT investigation of fluorinated methyl hydroperoxides: Structures, rotational barriers, and thermochemical properties

Ab initio and density functional theory (DFT) calculations have been performed on CH₂FOOH, CHF₂OOH, CF₃OOH, CF₂ClOOH, and CFCl₂OOH. Geometries of stable conformers are optimized at the MP2(FULL)/6-31G(d,p) and B3LYP/6-31G(d,p) levels of theory. The enthalpies of formation () and the ROOH, ROOH, and ROOH bond dissociation enthalpies (BDEs) are estimated for each of the studied hydroperoxides using the calculated reaction enthalpies () of the adopted isodesmic reactions. The results show that the progressive fluorine substitution of hydrogen atoms in methyl group results in an increase in each of BDE(OH), BDE(OO), and BDE(CO). This has been explained in terms of the stabilizing influence of fluorine-substituted methyl groups. However, the replacement of F by Cl when going from CF₃OOH to CFCl₂OOH leads to a decrease in both BDE(OO) and BDE(CO). Potential energy barriers for internal rotation about CO and OO are calculated at the B3LYP/6-31G(d,p) level for each of the studied hydroperoxides.     

Synthesis, structure, band gap, and electronic structure of CsAgSb4S7

The compound CsAgSb₄S₇ has been synthesized by the reaction of the elements in a Cs₂S₃ flux at 773 K. The compound crystallizes in a new structure type with eight formula units in space group C2/c of the monoclinic system in a cell at 153 K of dimensions , , , β=97.650(1)°, and . The structure contains two-dimensional layers separated by Cs atoms. Each layer is built from edge-sharing one-dimensional and chains. Each Ag atom is tetrahedrally coordinated to four S atoms. Each Sb³⁺ center is pyramidally coordinated to three S atoms to form an SbS₃ group. CsAgSb₄S₇ is insulating with an optical band gap of 2.04 eV. Extended Hückel calculations indicate that the band gap in CsAgSb₄S₇ is dominated by the Sb 5s and S 3p states above and below the Fermi level.     

Synthesis and characterization of the rare-earth dicyanamides Ln[N(CN)2]3 with Ln=La, Ce, Pr, Nd, Sm, and Eu

The rare-earth dicyanamides Ln[N(CN)₂]₃ (Ln=La, Ce, Pr, Nd, Sm, Eu) were obtained via ion exchange in aqueous medium and subsequent drying: The crystal structures were solved and refined based on X-ray powder diffraction data and they were found to be isotypic: Ln[N(CN)₂]₃; Cmcm (no. 63), Z=4, Ln=La: , , ; Ce: , , ; Pr: , , ; Nd: , , ; Sm: , , ; Eu: , , ). The compounds represent the first dicyanamides with trivalent cations. The Ln³⁺ ions are coordinated by three bridging N atoms and six terminal N atoms of the dicyanamide ions forming a three capped trigonal prism. The structure type is related to that of PuBr₃. The novel compounds Ln[N(CN)₂]₃ have been characterized by IR and Raman spectroscopy (Ln=La) and the thermal behavior has been monitored by differential scanning calorimetry (Ln=Ce, Nd, Eu).     

Zn3(HPO3)4·Zn(H2O)6: a purely inorganic open-framework zincophosphite with octahedral zinc complex [Zn(H2O)6] encapsulating in the channels

The hydrothermal synthesis and single crystal structure of Zn₃(HPO₃)₄·Zn(H₂O)₆ are reported. The structure is built-up from vertex linking ZnO₄ tetrahedral and HPO₃ pseudo-pyramids units, giving rise to a three-dimensional framework with large 8, 16-membered ring channels. The zincophosphite is purly inorganic with the octahedral zinc complex filled in the channel. The synthesis of system required the presence of the organic amine which is not incorporated into the structure of the product. The framework-metal complex encapsulating in the channel is the first time appeared in open-framework zincophospates and zincophosphites. Crystal data: Zn₃(HPO₃)₄·Zn(H₂O)₆, M=689.52, orthorhombic, Fddd (No. 70), , , , , Z=8, , , R=0.0265, R_w=0.0406.     

Crystal structures of Rb2U2O7 and Rb8U9O31, a new layered rubidium uranate

Two alkali metal uranates Rb₂U₂O₇ and Rb₈U₉O₃₁ have been synthesized by solid state reaction at high temperature and their crystal structures determined from single crystal X-ray diffraction data, collected with a three circles Brucker SMART diffractometer equipped by Mo(Kα) radiation and a charge-coupled device (CCD) detector. Their structures were solved using direct methods and Fourier difference techniques and refined by a least-square method on the basis of F² for all unique reflections, with R₁=0.043 for 53 parameters and 746 independent reflections with I?2σ(I) for Rb₂U₂O₇, monoclinic symmetry, space group P2₁/c, , , , β=108.81(1)°, , , Z=2 and R₁=0.036 for 141 parameters and 2065 independent reflections with I?2σ(I) for Rb₈U₉O₃₁, orthorhombic, space group Pbna, , , , , , Z=4.The Rb₂U₂O₇ structure presents a strong analogy with that of K₂U₂O₇ and can be described by layers of distorted UO₂(O₄) octahedra built from dimeric units of edge shared octahedra further linked together by opposite corners. In Rb₈U₉O₃₁ puckered layers are formed by the association of two different uranium polyhedra, pentagonal bipyramids and distorted octahedra. The structure of Rb₈U₉O₃₁ is built from a regular succession of infinite ribbons similar to those observed in diuranates M₂U₂O₇ (MK, Rb) and infinite three polyhedra wide ribbons , to create an original undulated sheets .For both compounds Rb⁺ ions occupy the interlayer space and exhibit comparable mobility with conductivity measurements indicating an Arrhenius-type behavior.     

In3Ir3B, In3Rh3B and In5Ir9B4, the first indium platinum metal borides

The first indium platinum metal borides have been synthesized and structurally characterized by single crystal X-ray diffraction data. In₃Ir₃B and In₃Rh₃B are isotypic. They crystallize with the hexagonal space group and Z=1. The lattice constants are , for In₃Ir₃B and , for In₃Rh₃B. The structure which is derived from the Fe₂P type is characterized by columns of boron centered triangular platinum metal prisms inserted in a three-dimensional indium matrix. The indium atoms are on split positions. In₅Ir₉B₄ (hexagonal, space group , , , Z=1) crystallizes with a structure derived from the CeCo₃B₂ type. The structure can be interpreted as a layer as well as a channel structure. In part the indium atoms are arranged at the vertices of a honeycomb net (Schlaefli symbol 6³) separating slabs consisting of double layers of triangular Ir₆B prisms, and in part they form a linear chain in a hexagonal channel formed by iridium prisms and indium atoms of the honeycomb lattice.     

Monitoring structural transformations in crystals. Part 4. Monitoring structural changes in crystals of pyridine analogs of chalcone during [2+2]-photodimerization and possibilities of the reaction in hydroxy derivatives

We studied the [2+2]-photodimerization in crystals of pyridine analogs and hydroxy derivatives of chalcone using the X-ray structure analysis. The mutual orientation of adjacent molecules in the crystals was analyzed in a quantitative way and the results were compared with data for known photoactive crystals undergoing the [2+2]-photodimerization. In the case of one pyridine analog, we processed the single-crystal-to-single-crystal photodimerization and determined the structure for the mixed crystal containing both the substrate and the product. We also explained a role of hydrogen bonds in the [2+2]-photodimerization in the case of the hydroxy derivatives of chalcone. C₅H₄N-CO-CHCH-C₆H₅: , , , β=91.318(10)°, monoclinic, . The irradiated crystal of the above analog: , , , β=91.870(10)°, monoclinic, . C₆H₅-CO-CHCH-C₅H₄N: , , , β=110.01(3)°, monoclinic, C2/c,Z=8. C₆H₅-CO-CHCH-C₆H₄(o-OH): , , , β=109.73(5)°, monoclinic, . C₆H₅-CO-CHCH-C₆H₄(p-OH): , , , orthorhombic, .     

Syntheses, characterization and sensitized lanthanide luminescence of heteronuclear Pt-Ln (Ln = Eu, Nd, Yb) complexes with 2,2′-bipyridyl ethynyl ligands

Reaction of [Pt()Cl]⁺ ( = 4,4′,4′′-tri-tert-butyl-2,2′:6′,2′′-terpyridine) with 5-ethynyl-2,2′-bipyridine (HCCbpy) or 5,5′-bis(trimethylsilylethynyl)-2,2′-bipyridine (Me₃SiCCbpyCCSiMe₃) in the presence of cuprous iodide gives [Pt(^tBu₃tpy)(CCbpy)]⁺ (1) or [{Pt()}₂(CCbpyCC)]²⁺ (2) through Pt-acetylide σ-coordination, respectively. Incorporating 1 or 2 with Ln(hfac)₃(H₂O)₂ through 2,2′-bipyridyl chelating the Ln^III (Ln = Nd, Eu, and Yb) centers induces formation of a series of [Pt()(CCbpy){Ln(hfac)₃}]⁺ (PtLn) or [{Pt()}₂(CCbpyCC){Ln(hfac)₃}]²⁺ (Pt₂Ln) complexes, respectively. The structures of binuclear platinum(II) complex 2(PF₆)₂ and heterobinuclear PtNd complex 3(CF₃COO) were determined by single crystal X-ray diffraction. Both 1 and 2 exhibit typical low-energy absorption bands in near UV-Vis region, ascribed to dπ(Pt) → π^∗() MLCT and π(CCbpy/CCbpyCC) → π^∗() LLCT transitions. Upon formation of the PtLn or PtLn₂ complexes, the low-energy absorption bands are obviously blue-shifted (15-20 nm) compared with those in the Pt^II precursor 1 or 2. With excitation at 350 nm < λ < 550 nm which is the absorption region of MLCT and LLCT transitions, sensitized luminescence that is characteristic of the corresponding lanthanide(III) ions occurs in both PtLn and Pt₂Ln complexes. In contrast, Pt-based luminescence from the MLCT and LLCT states are mostly quenched in these Pt-Ln heteronuclear complexes, revealing that quite effective Pt → Ln energy transfer is operating from the Pt()(acetylide) chromophore to the lanthanide(III) centers.     

Crystal growth, characterization and physical properties of PrNiSb3, NdNiSb3 and SmNiSb3

The crystal structures of three new intermetallic ternary compounds in the LnNiSb₃ (Ln=Pr, Nd and Sm) family have been characterized by single crystal X-ray diffraction. PrNiSb₃, NdNiSb₃ and SmNiSb₃ all crystallize in an orthorhombic space group, Pbcm (No. 57), Z=12, with , , , and ; , , , and ; and , , , and , for Ln=Pr, Nd and Sm, respectively. These compounds consist of rare-earth atoms located above and below layers of nearly square, buckled Sb nets, along with layers of highly distorted edge- and face-sharing NiSb₆ octahedra. Resistivity data indicate metallic behavior for all three compounds. Magnetization measurements show antiferromagnetic behavior with (PrNiSb₃), 4.6 K (NdNiSb₃), and 2.9 K (SmNiSb₃). Effective moments of 3.62 μ_B, 3.90 μ_B and 0.80 μ_B are found for PrNiSb₃, NdNiSb₃ and SmNiSb₃, respectively, and are consistent with Pr³⁺ (f ²), Nd³⁺ (f ³), and Sm³⁺ (f ⁴).     

(NH3CH2CH2NH3)B6O9(OH)2: Synthesis and crystal structure of a novel layered borate templated by ethylenediamine

A novel intercalated borate compound (NH₃CH₂CH₂NH₃)B₆O₉(OH)₂, has been solvothermally synthesized, and structurally characterized by single crystal X-ray diffraction. Compound crystallizes in the monoclinic, space group P2(1)/c, , , , β=93.32(3)°, , Z=4. Its oxoborate structure is built up from 1-D polyborate chains with 3, 11-membered boron rings bonded diamine molecules through electrostatic attraction and hydrogen bond interactions to construct 2-D layered compound. Other characterizations by IR, element analysis, thermal analysis and specific surface area are also discussed.     

Thermoelectric properties and antiferromagnetism of the new ternary transition metal telluride CrAuTe4

The new ternary transition metal telluride CrAuTe₄ has been discovered through solid-state reaction of the elements. The crystal structure is solved in the monoclinic space group P2/m (No. 10) with lattice parameters , , , and β=90.604(10)°. The structure is related to that of the binary compound AuTe₂, and a derivation of the structure of CrAuTe₄ from AuTe₂ is shown. Measurements of the thermopower, thermal conductivity, electrical resistivity, and magnetic susceptibility are presented. The compound undergoes a paramagnetic to antiferromagnetic transition at .     

Crystal structure of the pyrochlore oxide superconductor KOs2O6

We report the single-crystal X-ray analysis of the structure of the pyrochlore oxide superconductor KOs₂O₆. The structure was identified as the β-pyrochlore structure with space group and lattice constant at : the K atom is located at the 8b site, not at the 16d site as in conventional pyrochlore oxides. We found an anomalously large atomic displacement parameter at for the K cation, which suggests that the K cation weakly bound to an oversized Os₁₂O₁₈ cage exhibits intensive rattling, as recently observed for clathrate compounds. The rattling of A cations is a common feature in the series of β-pyrochlore oxide superconductors AOs₂O₆ (A=Cs, Rb and K), and is greatest for the smallest K cation.     

Structures of the reduced niobium oxides Nb12O29 and Nb22O54

The crystal structure of Nb₂₂O₅₄ is reported for the first time, and the structure of orthorhombic Nb₁₂O₂₉ is reexamined, resolving previous ambiguities. Single crystal X-ray and electron diffraction were employed. These compounds were found to crystallize in the space groups P2/m (, , , β=102.029(3)^°) and Cmcm (, , ), respectively and share a common structural unit, a 4×3 block of corner sharing NbO₆ octahedra. Despite different constraints imposed by symmetry these blocks are very similar in both compounds. Within a block, it is found that the niobium atoms are not located in the centers of the oxygen octahedra, but rather are displaced inward toward the center of the block forming an apparent antiferroelectric state. Bond valence sums and bond lengths do not show the presence of charge ordering, suggesting that all 4d electrons are delocalized in these compounds at the temperature studied, T=200 K.     

Syntheses and crystal structures of three new borates templated by transition-metal complexes in situ

Three new cobalt borate compounds, [Co(DIEN)₂][B₅O₆(OH)₄]₂ (DIEN=diethylenetriamine) (1), [B₅O₇(OH)₃Co(TREN)] (TREN=tris(2-aminoethyl)amine) (2), and [Co₂(TETA)₃][B₅O₆(OH)₄]₄ (TETA=triethylenetetramine) (3) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR, elemental analysis and thermogravimetry. The structures exhibit interesting 3D supramolecular hydrogen-bonded architectures, involving the similar borate polyanion [B₅O_6+n(OH)_4−n]⁽ⁿ⁺¹⁾⁻(n=0 for 1 and 3, and n=1 for 2) and the templating transition metal complexes which are generated in situ under mild solvothermal conditions. Crystal data: 1, monoclinic, space group C2/m (No. 12), , , , β=93.601(4)°, , Z=2; 2, monoclinic, P2₁/c (No. 14), , , , β=99.926(4)°, , Z=4; 3, triclinic, space group P-1 (No. 2), , , , α=77.009(5)°, β=80.095(2)°, γ=82.334(3)°, , Z=2.